Present invention relates to an abnormal detection apparatus for a cable including a power supply line used in a car.
An electrical fuse is used for overcurrent protection in the event of a short circuit to ground in a power supply line used in a motor vehicle, such as a car. The power supply line is generally provided so as to form a star type architecture around a battery, and the electrical fuse is located at the nearest location to the battery.
When a ground short circuit occurs in a power supply line, that portion of the power supply line connected downstream of the electric fuse is interrupted, and it thus becomes impossible to supply electric power over the power supply line. Thus, one part of the necessary function of the power supply line stops. Such ground short circuits are shown in Japanese Patent Laid-open Nos. 58-103704 (1983) and 58218709 (1983), and Japanese Utility-model Laid-open No. 1-102777 (1989).
A loop formation type power supply line is one of the power supply lines which do not lose a needed function even if the ground short circuit occurs.
The loop formation type power supply line supplies the power in two directions, the needed function is not lost for the power supply line interception in the ground short circuit.
As the power source is supplied in two directions in a power supplying line of loop type formation, the place where the ground short circuit occurs should be detected, and only the place should be intercepted. However, it is difficult to detect the ground short circuit of the power supply line in the function. Therefore, if the abnormality of the power supply line may be detected previously, any suitable countermeasures are taken before the abnormality occurs in the power supply line, thereby reliability is improved and a needed function may be kept.